The present invention generally relates to firearms, and more particularly to gas piston operating systems for auto-loading semi-automatic and automatic firearms.
Gas operating systems are known for cycling the action in auto-loading semi-automatic and automatic rifles. These systems basically use a portion of the high energy combustion gases from discharging the firearm to cycle the action for extracting a spent cartridge case and chambering a new round. One type of known system is a gas piston system used in AK-47 and AR-18 type rifles. These piston systems, also called blowback systems, are generally described in U.S. Pat. Nos. 5,520,019; 4,475,438; and 3,618,457; all of which are incorporated herein by reference in their entireties. A portion of the expanding combustion gases produced by discharging the rifles are ported from the barrel into a cylindrical piston bore containing an axially-movable reciprocating gas piston. The gas acts on the face of the piston driving it abruptly and rapidly rearward. An operating or transfer rod mechanically links the piston to a reciprocating bolt carrier slidably supported in the receiver disposed rearward at the breech end of the barrel. The bolt carrier, which carries a reciprocating and typically rotatable breech bolt, is thrust rearward by a brief but forceful impact by the transfer rod to open the breech, and extract and eject the spent case. The bolt carrier is then returned forward in some designs by a return/recoil spring to automatically load a new cartridge into the chamber from the magazine and reclose the breech in preparation for firing the next round. Such recoil spring systems are generally described U.S. Pat. Nos. 2,951,424 and 4,475,438, which are incorporated herein by reference in their entireties.
The foregoing gas piston systems are sometimes prone to rattling and wear of components due to a loose fit and/or physical gaps that may exist between the piston, transfer rod, and bolt carrier prior to firing a round. When the firearm is discharged, the piston is rapidly accelerated rearward under the full pressure force of the combustion gases entering the piston bore (i.e. constant recoil mechanisms operating under a single pressure force). Accordingly, the piston is moved from complete stop to full speed in a fraction of a second in a single stage piston actuation process. This creates high instantaneous forces and stresses on the mechanical linkage and contact surfaces between the piston, transfer rod, and bolt carrier.
An improved gas piston operating system is desirable.